preformation

/,pri:fɔ:'meiʃn/

Thân thiện

A scientist in the 18th century studies a diagram of a homunculus to explain the theory of preformation.

Definition

1. Noun:
   • A biological theory: "Preformation" refers to the historical biological theory that organisms develop from miniature, fully formed versions of themselves that exist in the germ cell (sperm or egg). This miniature organism was often called a homunculus.
   • The state of being preformed: More generally, it can denote the act or process of forming or shaping something in advance.

Usage and Examples

• Noun (Historical Theory):

  • The theory of preformation was eventually replaced by the theory of epigenesis.
  • Early microscopists believed they saw a homunculus in sperm cells, supporting the idea of preformation.

• Noun (General Concept):

  • The preformation of the plan allowed for a smooth execution. (This usage is less common and more formal.)

Advanced Usage and Notes

• Historical Context: The term "preformation" is primarily used in historical and philosophical discussions of biology. It is contrasted with epigenesis, the theory that an organism develops progressively from an undifferentiated state.
• "Preformationism": This related term is often used synonymously with "preformation" to name the theory itself.
  • Preformationism was a dominant theory in the 17th and 18th centuries.

Variants and Related Words

• Preformationism (n): The doctrine or theory of preformation.
• Preform (v): To form or shape beforehand.
• Preformative (adj): Relating to or involving preformation.
• Homunculus (n): The supposed miniature, fully formed human believed to be contained within a germ cell according to preformation theory.

Synonyms

• Preformism: (Rare) Another term for the theory of preformation.
• Predelineation: (General) The act of outlining or forming something in advance.

Antonyms

• Epigenesis: The theory that an embryo develops from an undifferentiated egg cell through successive stages of differentiation, opposing the concept of preformation.

Học thuật

Noun

1. a theory (popular in the 18th century and now discredited) that an individual develops by simple enlargement of a tiny fully formed organism (a homunculus) that exists in the germ cell

Từ đồng nghĩa

• theory of preformation